Video display apparatus and video display method

ABSTRACT

An image display device well suited for a multi-scanning type monitor includes a video signal measurement circuit that detects a horizontal synchronization frequency fH and a vertical synchronization frequency fV from an input image signal that conforms to the GTF Standard. A main control portion calculates timing data relative to a waveform of the signal ( 21 ) using the frequencies fH and fV, calculates adjustment parameters for adjusting a size and a position using this timing data, and sets the adjustment parameters to deflection control circuits, so that an image of the image signal may be displayed well on a CRT. Since the timing data is calculated using the synchronization frequencies fH and fV of the input image signal, it is possible to save on a memory capacity without storing timing data that corresponds to a plurality of different kinds of image signals.

TECHNICAL FIELD

The present invention relates to image display device and method thatcan display an image in accordance with a plurality of kinds of inputimage signals.

More specifically, the present invention relates to image display deviceand method that, using a horizontal synchronization frequency and avertical synchronization frequency detected from an input image signal,calculate timing data relative to a waveform of the input image signaland, using the timing data, calculate an adjustment parameter foradjusting an image display state and, based on the adjustment parameter,display an image relative to the input image signal, thereby eliminatinga necessity of storing the timing data corresponding to the plurality ofkinds of image signals for the purpose of obtaining the adjustmentparameter corresponding to the plurality of kinds of image signals, thusenabling saving on a memory capacity.

Further, the present invention relates to image display device andmethod that, using timing data relative to a waveform of an input imagesignal, calculate an adjustment parameter for adjusting an image displaystate, set the adjustment parameter to a deflection control circuit,then measure a delay of a deflection pulse with respect to a horizontalsynchronization signal of the input image signal, and alter a value of ahorizontal position parameter to re-set it to the deflection controlcircuit so that the delay may be equal to a target value, therebyenabling setting a horizontal display position at a right position evenif a deflection system is deteriorated over time.

BACKGROUND ART

Information processing apparatus including a personal computer, whichuses a variety of image display devices such as a Cathode Ray Tube (CRT)or an Liquid Crystal Display (LCD), have been adapted to output variouskinds of image signals according to different manufacturers, types, etc.Therefore, as an image display device having a function that canaccommodate these various kinds of image signals, a device so-called amulti-scanning type monitor has been developed recently.

The following will describe an image signal (video signal) input from atypical information processing apparatus to an image display device,with reference to FIGS. 14 and 15. FIG. 14 shows a waveform of the videosignal in its one horizontal scanning period and FIG. 15, a signalwaveform of the video signal in its one vertical scanning period.

As shown in FIG. 14, each of the horizontal scanning periods is definedby a horizontal synchronization signal SYNCH having a constant cycle.Each of the horizontal scanning periods is comprised of a pulse widthinterval of the horizontal synchronization signal SYNCH, a back porchinterval BPH, a horizontal active interval ACTH, and a front porchinterval FPH. In the horizontal active interval ACTH of these, an imageis actually displayed horizontally on a screen, while the back porchinterval BPH and the front porch interval FPH are displayed as blackborders at right and left ends respectively on the screen.

Further, as shown in FIG. 15, each of the vertical scanning periods isdefined by a vertical synchronization signal SYNCV having a constantcycle. Each of the vertical scanning periods is comprised of a pulsewidth interval of the vertical synchronization signal SYNCV, a backporch interval BPV, a vertical active interval ACTV, and a front porchinterval FPV. In the vertical active interval ACTV of these, an image isactually displayed vertically on the screen, while the back porchinterval BPV and the front porch interval FPV are displayed as blackborders at top and bottom ends respectively on the screen.

As shown in FIGS. 14 and 15, an image signal has a few timing factors(hereinafter referred to as “timing data”), so that if even only one ofthem is different, the image signal is different in kind. For example,typically, image signals having different frequencies (horizontalsynchronization frequencies) of the horizontal synchronization signalsSYNCH generally have the different back porch intervals BPH, horizontalactive intervals ACTH, or even front porch intervals FPH. This holdstrue also in the vertical direction.

Kinds of such image signals are different with the corresponding devicessuch as a computer or a video card from which the image signal isoutputted, thus numbering a few hundreds of kinds conceivably. Themulti-scanning type monitor described above is required to be capable ofdisplaying any kind of an image signal input thereto on its screen witha right size at a right position. Therefore, to accommodate such arequirement, the following methods have been employed conventionally.

A first method is as follows. That is, beforehand, at a factory, animage signal having known timing data is actually input to an imagedisplay device and make an adjustment so that an image may be displayedwith a predetermined size at a predetermined position on a screen of thedevice, and the adjustment value (adjustment parameter) of thiscondition is written into a nonvolatile memory etc. corresponding to akind of the image signal. Such the processes for adjustment andadjustment-value write-in are performed for all known image signals thatare expected to be used. In actual use, on the other hand, the kind ofan image signal input from a computer of a user is checked, so that anadjustment parameter corresponding to the kind is read out of thenonvolatile memory and used for the display.

A second method is as follows. That is, in actual use, all items oftiming data relative to an input image signal are measured, so thatbased on the timing data, predetermined arithmetic operations areperformed to obtain an adjustment parameter, which is in turn used forthe display. In this case, in contrast to the first method, it is notnecessary to perform adjustment at the factory beforehand.

However, for the first method, at the factory, it is necessary to adjusta few adjustment parameters for each kind of image signal, so that if afew hundreds of kinds of image signals are to be accommodated,adjustment is necessary each time the image signal to be input isswitched, thus consuming much time and labor, which is a problem. Tosolve this problem, such a method may also be thought of that, forexample, a size and a position of a display region on a screen aredetected by sensors and then subject to automatic adjustment so thatthey may be optimized. However, this method needs to provide anautomatic adjusting machine, thus contributing to an increase inmanufacturing cost.

Further, for the second method, all items of the timing data relative toan input image signal are measured, so that based on the measured value,an adjustment parameter is calculated, thus deteriorating an adjustmentaccuracy if an error occurs in measurement, which is a problem. Inparticular, if the image signal has a high frequency or a small activeinterval (e.g., in a case where the signal represents a dot or a line),a large error may possibly occur in measurement to deteriorate theadjustment accuracy significantly. Furthermore, it takes rather longtime to measure the timing data relative to the image signal, thusprolonging a lapse of time from a moment when the image signal is inputto a moment when a proper image appears on the screen, which is aproblem.

To solve these problems, the present applicant has earlier proposed amethod for first storing in storage means timing data relative to signalwaveforms for each kind of an image signal, and, in actual use,detecting the kind of the input image signal to calculate an adjustmentparameter using the timing data that corresponds to the kind of theimage signal which has been stored in the storage means, thus displayingan image based on the adjustment parameter (see Japanese PatentPublication No. H11-52934). This method eliminates the problems of thefirst and second methods described above.

However, this method is adapted to store timing data that corresponds toa plurality of kinds of image signals and so requires a mass capacitymemory, thus increasing costs of the device as a whole, which is aproblem.

Further, this method of calculating an adjustment parameter using timingdata that corresponds to a kind of an image signal in order to displayan image based on the adjustment parameter has another problem that theimage cannot be displayed at a right horizontal position if a deflectionsystem is deteriorated over time.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to eliminate a necessity ofstoring timing data that corresponds to a plurality of kinds of imagesignals in order to obtain adjustment parameters corresponding to theplurality of kinds of image signals, thus saving on a memory capacity.

It is another object of the present invention to enable setting ahorizontal display position at a right position even if a deflectionsystem is deteriorated over time, when displaying an image based on acalculated adjustment parameter.

An image display device related to the present invention comprisesdetection means for detecting a horizontal synchronization frequency anda vertical synchronization frequency of an input image signal, firstarithmetic operation means for calculating timing data relative to awaveform of the input image signal using the horizontal synchronizationfrequency and the vertical synchronization frequency that are detectedby the detection means, second arithmetic operation means forcalculating an adjustment parameter for adjusting an image display stateusing the timing data calculated by the first arithmetic operationmeans, and image display means for displaying an image relative to theinput image signal based on an adjustment parameter calculated by thesecond arithmetic operation means.

An image display method related to the present invention comprises thesteps of detecting a horizontal synchronization frequency and a verticalsynchronization frequency of an input image signal, calculating timingdata relative to a waveform of the input image signal using thehorizontal synchronization frequency and the vertical synchronizationfrequency thus detected, calculating an adjustment parameter foradjusting an image display state using the timing data thus calculated,and displaying an image relative to the input image signal, based on theadjustment parameter thus calculated.

By the present invention, a horizontal synchronization frequency and avertical synchronization frequency are detected from an input imagesignal. The input image signal is such that timing factors of the imagesignal can be obtained by arithmetic operations as far as a horizontalsynchronization frequency and a vertical synchronization frequency areknown. For example, the image signal conforms to the Generalized TimingFormula (GTF) Standard of the Video Electronics Standards Association(VESA).

The timing data relative to a waveform of the input image signal iscalculated using the horizontal synchronization frequency and thevertical synchronization frequency that are detected from the inputimage signal. Then, using the timing data is calculated an adjustmentparameter for adjusting an image display state such as a size or aposition, and then based on this adjustment parameter is displayed animage relative to the input image signal.

In such a manner, the horizontal synchronization frequency and thevertical synchronization frequency that are detected from the inputimage signal are used to calculate timing data relative to a waveform ofthe input image signal, and this timing data is in turn used tocalculate the adjustment parameter for adjusting the image displaystate, so that a necessity of storing timing data corresponding to aplurality of kinds of image signals is eliminated, thus enabling savingon a memory capacity.

It is to be noted that by storing calculated adjustment parameters instorage means with them associated with the horizontal synchronizationfrequency and the vertical synchronization frequency, and when apredetermined one of the adjustment parameters that corresponds to thehorizontal synchronization frequency and the vertical synchronizationfrequency that are detected from the input image signal is present inthe storage means, an image relative to the input image signal can bedisplayed on the basis of the predetermined adjustment parameter tothereby immediately acquire the same kind of image signal from thestorage means, if the same kind of image signal is input, withoutcalculating timing data or adjustment parameters, in order to reduce alapse of time from a moment when the image signal is input to a momentwhen the image is displayed, thus improving a response.

Another image display device related to the present invention comprisestiming data acquisition means for acquiring timing data relative to awaveform of an input image signal, first calculation means forcalculating adjustment parameters each for adjusting an image displaystate using the timing data acquired by the timing data acquisitionmeans, setting means for setting the adjustment parameters calculated bythe first calculation means to a deflection control circuit, delaymeasurement means for measuring a delay of a deflection pulse withrespect to a horizontal synchronization signal of the input imagesignal, and re-setting means for altering a value of a horizontalposition adjustment parameter of the adjusting parameters, thehorizontal position adjustment parameter adjusting image region positionin a horizontal direction, so that a delay measured by the delaymeasurement means may be equal to a target delay and for re-setting itto the deflection control circuit.

Another image display method related to the present invention comprisesthe steps of acquiring timing data relative to a waveform of an inputimage signal, calculating adjustment parameters each for adjusting animage display state using the acquired timing data, setting thecalculated adjustment parameters to a deflection control circuit,measuring a delay of a deflection pulse with respect to a horizontalsynchronization signal of the input image signal, and altering a valueof a horizontal position adjustment parameter of the adjustingparameters, the horizontal position adjustment parameter adjusting imageregion position in a horizontal direction, so that the measured delaymay be equal to a target delay and for re-setting it to the deflectioncontrol circuit.

In the present invention, timing data relative to a waveform of an inputimage signal is acquired. For example, a kind of the input image signalis detected, so that timing data corresponding to the detected kind ofthe input image signal is read out of data storage means in which thetiming data relative to respective signal waveforms for each of theimage signal kinds is stored.

It is to be noted that when there is no timing data in the data storagemeans that corresponds to a kind of an input image signal, timing datarelative to the waveform of the input image signal is calculated using,for example, the horizontal synchronization frequency and the verticalsynchronization frequency that are detected from the input image signal.

Further, for example, without utilizing the data storage means in whichtiming data is stored, the horizontal synchronization frequency and thevertical synchronization frequency of the input image signal aredetected, and timing data relative to the waveform of the input imagesignal is calculated using the detected horizontal and verticalsynchronization frequencies.

Then, using this timing data is calculated the adjustment parameterseach for adjusting an image display state such as a size and a position,and these adjustment parameters are set to a deflection control circuitso that based on the adjustment parameters, an image relative to theinput image signal may be displayed.

Then, a delay of a deflection pulse with respect to the input imagesignal is measured. In this case, if a deflection system is notdeteriorated over time, by setting the calculated horizontal positionadjustment parameter to the deflection control circuit, the delaybecomes equal to a target delay value, so that a horizontal displayposition is set to a right position. If the deflection is deterioratedover time, on the other hand, this delay becomes different from thetarget delay value.

Therefore, a value of the horizontal position adjustment parameter isaltered and re-set to the deflection control circuit so that thismeasured delay may be equal to the target delay value. With this, thehorizontal display position is set to a right position even if thedeflection system is deteriorated over time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram for showing a configuration of an imagedisplay device according to a first embodiment;

FIG. 2 is an explanatory diagram of contents of an adjustment parametertable in a nonvolatile memory;

FIG. 3 is an explanatory diagram of an intrinsic property data storagearea in the nonvolatile memory;

FIGS. 4A and 4B are diagrams each for showing the respective waveformand horizontally deflection pulse of an input video signal in onehorizontal scanning period;

FIG. 5 is a diagram for showing a waveform of the input video signal inone vertical scanning period;

FIG. 6 is a flowchart for showing processing for setting an adjustmentparameter;

FIG. 7 is an explanatory diagram showing how to obtain a horizontal sizeadjustment parameter;

FIG. 8 is an explanatory diagram showing how to obtain a horizontalposition adjustment parameter;

FIG. 9 is another explanatory diagram showing how to obtain thehorizontal position adjustment parameter;

FIG. 10 is a block diagram for showing a configuration of an imagedisplay device according to a second embodiment;

FIG. 11 is an explanatory diagram showing contents of a timing datatable in a nonvolatile memory;

FIG. 12 is a flowchart for showing processing for setting an adjustmentparameter;

FIG. 13 is a flowchart for showing convergent processing of a delay;

FIG. 14 is a diagram for showing a waveform of a video signal in onehorizontal scanning period; and

FIG. 15 is a diagram for showing a waveform of a video signal in onevertical scanning period.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe a first embodiment of the present invention.FIG. 1 shows a configuration of an image display device 100 according tothe first embodiment. The image display device 100 is constituted as amulti-scanning type monitor available for use in a plurality of kinds ofimage signals (hereinafter called “video signals”) each of whichconforms to the VESA's GTF Standard.

The image display device 100 comprises a main control portion 11, anonvolatile memory 12, a video output circuit 13, a horizontaldeflection control circuit 14, a vertical deflection control circuit 15,and a video signal measurement circuit 16 that are interconnectedthrough a system bus 10. Here, a term “kinds” of the video signal meansthe kinds of a video signal that can be identified by a frequency of asynchronization signal.

Further, the image display device 100 comprises an input/outputinterface (I/F) circuit 17 for interconnecting the main control portion11 and an information processor (main body of a computer), not shown, ahorizontal deflection pulse output circuit 18 connected to an output endof the horizontal deflection control circuit 14, a vertical deflectionpulse output circuit 19 connected to an output end of the verticaldeflection control circuit 15, and a Cathode Ray Tube (CRT) 20 fordisplaying an image under the control of the video output circuit 13,the horizontal deflection pulse output circuit 18 and the verticaldeflection pulse output circuit 19.

The main control portion 11 comprises a Central Processing Unit (CPU) 11a, a Read Only Memory (ROM) 11 b in which a control program executed bythe CPU11 a and necessary data are stored, and a Random Access Memory(RAM) 11 c used as a work memory by the CPU11 a, thereby controllingoperations of the various portions.

The nonvolatile memory 12 comprises, for example, an ElectricallyErasable and Programmable ROM (EEPROM), including at least an adjustmentparameter table 12 b and an intrinsic property data storage area 12 c.

The adjustment parameter table 12 b is a user table which has such acharacteristic that when a user uses the present device, itsconfiguration data pieces (adjustment parameters) are added theretosequentially, having a configuration shown in, for example, FIG. 2described later. The intrinsic property data storage area 12 c is anarea which stores property data that indicates intrinsic displayproperties measured on the relevant image display device at a factorybeforehand, having contents shown in, for example, FIG. 3 describedlater.

The video output circuit 13 generates an RGB video signal 22 byperforming predetermined signal processing on an input video signal 21based on an instruction sent via the system bus 10 from the controlportion 11 and supplies it to the CRT20.

The horizontal deflection control circuit 14 supplies the horizontaldeflection pulse output circuit 18 with a deflection control signal forcontrolling horizontal deflection of an electron beam in the CRT20,according to control data (specifically, a horizontal size adjustmentparameter and a horizontal position adjustment parameter) which is setby the main control portion 11. The vertical deflection control circuit15 supplies the vertical deflection pulse output circuit 19 with adeflection control signal for controlling vertical deflection of theelectron beam in the CRT20, according to control data (specifically, avertical size adjustment parameter and a vertical position adjustmentparameter) which is set by the main control portion 11.

The horizontal deflection pulse output circuit 18 performs predeterminedsignal processing such as waveform shaping on the deflection controlsignal input from the horizontal deflection control circuit 14 andapplies it as a horizontal deflection pulse 23 to a horizontaldeflection yoke (not shown) of the CRT20. The vertical deflection pulseoutput circuit 19 performs predetermined signal processing such aswaveform shaping on the deflection control signal input from thevertical deflection control circuit 15 and applies it as a verticaldeflection pulse 24 to a vertical deflection yoke (not shown) of theCRT20.

As described later, the horizontal deflection pulse 23 is set so as tohave the same frequency as that of the horizontal synchronization signalin the input video signal 21. Each time one of the horizontal deflectionpulses 23 is applied to the horizontal deflection yoke of the CRT20, onehorizontal line is scanned. The vertical deflection pulse 24 is set soas to have the same frequency as that of the vertical synchronizationsignal in the input video signal 21. Each time one of the verticaldeflection pulses 24 is applied to the vertical deflection yoke of theCRT20, one frame is scanned.

The horizontal deflection pulse 23 is also input to the main controlportion 11 and the vertical deflection control circuit 15. The maincontrol circuit 11 forms a feedback loop together with the horizontaldeflection control circuit 14 and the horizontal deflection pulse outputcircuit 18, to conduct proper control on horizontal deflection inaccordance with a kind of the input video signal 21 input to the videooutput circuit 13. The vertical deflection control circuit 15 suppliesthe above-mentioned deflection control signal to the vertical deflectionpulse output circuit 19 each time it receives one frame of thehorizontal deflection pulse 23.

To the video signal measurement circuit 16, the same signal as the inputvideo signal 21 is input from the video output circuit 13. The videosignal measurement circuit 16 detects a frequency (horizontalsynchronization frequency fH, vertical synchronization frequency fV) ofa synchronization signal in the input video signal 21 and sends adetection result to the main control portion 11.

The main control portion 11 calculates timing data relative to awaveform of the input video signal 21 using a horizontal synchronizationfrequency and a vertical synchronization frequency that are sent fromthe video signal measurement circuit 16. This timing data contains itemsof the horizontal timing data t1, t2 and t3 and items of the verticaltiming data L1, L2 and L3.

The following will describe the items of horizontal timing data t1, t2and t3 and the items of vertical timing data L1, L2 and L3 withreference to FIGS. 4A and 4B and FIG. 5. It is to be noted that FIG. 4Ashows the waveform of the input video signal 21 in one horizontalscanning period, FIG. 4B shows timing of the horizontal deflection pulse23, and FIG. 5 shows the waveform of the input video signal 21 in onevertical scanning period.

As shown in FIG. 4A, the horizontal timing data t1 indicates a length ofa front-side front porch FPH of a horizontal synchronization signalSYNCH and the horizontal timing data t2 indicates a total-sum length ofthe horizontal synchronization signal SYNCH and its rear-side back porchBPH. The horizontal timing data t3 indicates a length of a horizontalactive interval ACTH sandwiched by the back porch BPH and the frontporch FPH, that is, the length of a substantial portion of the videosignal. This active interval corresponds to a horizontal width of animage region of a screen of the CRT20.

These items of data are given using a unit of, for example, microsecond[μs]. In the following description, an interval including the frontporch FPH, the horizontal synchronization signal SYNCH, and the backporch BPH (t1+t2) is referred to as a non-active horizontal interval. Itis to be noted that a cycle tH (=t1+t2+t3) of the horizontalsynchronization signal SYNCH is determined from a horizontalsynchronization frequency fH.

As shown in FIG. 4B, the horizontal deflection pulse 23 has a constantpulse width t4 and has its cycle set so as to be equal to a cycle tH ofthe horizontal synchronization signal SYNCH. However, its phase is setas shifted by δH with respect to the video signal. Specifically, it isset so that an offset δH may be present between a center of thenon-active interval of the video signal and a center of the pulse widthof the horizontal deflection pulse 23.

Originally, if the offset δH is 0, the center of the horizontal activeinterval ACTH of the video signal coincides with the center of the pulsewidth of the horizontal deflection pulse 23, this state is idealistic inorder that a center of the screen and that of the image display regionmay coincide with each other.

Actually, however, a delay characteristic of the horizontal deflectionyoke causes a horizontal-scan starting position of a beam to be shiftedby δH with respect to a position of the horizontal deflection pulse 23.Furthermore, this offset δH depends on a magnitude of a frequency of thehorizontal deflection pulse 23. Therefore, as described later, to placethe image display region at the center of the screen exactly, it isnecessary to properly set the offset δH in accordance with a frequencyof the horizontal deflection pulse, that is, the frequency of thehorizontal synchronization signal SYNCH.

As shown in FIG. 5, the vertical timing data L1 indicates a length of afront-side front porch FPV of a vertical synchronization signal SYNCVand the horizontal timing data 12 indicates a total-sum length of thevertical synchronization signal SYNCV and its rear-side back porch BPV.The vertical timing data L3 indicates a length of a vertical activeinterval ACTV sandwiched by the back porch BPV and the front porch FPV,that is, the length of a substantial portion of the video signal. Thisvertical active interval ACIV corresponds to a vertical width of theimage region of the screen of the CRT20.

The items of data are given using a unit of, for example, the number oflines. In the following description, an interval (L1+L2) including thefront porch FPV, the horizontal synchronization signal SYNCV, and theback porch BPV is referred to as a non-active vertical interval. It isto be noted that a cycle LV (=L1+L2+L3) of the vertical synchronizationsignal SYNCV is determined from a vertical synchronization frequency fV.

The following will describe a method for calculating the items ofhorizontal timing data t1, t2 and t3 and the items of vertical timingdata L1, L2 and L3 using a horizontal synchronization frequency fH (kHz)and a vertical synchronization frequency fV (Hz) that are sent from thevideo signal measurement circuit 16.

(A) Calculation of the Items of Horizontal Timing Data t1, t2 and t3:

A basic offset constant C′ [%] and a basic gradient constant M′ [%/kHz]are obtained by Equations (1) and (2), respectively.C′=(C−J)*K/256)+J  (1)M′=M*K/256  (2)In Equations (1) and (2), C indicates an extended offset constant [%], Mindicates an extended gradient constant [%/kHz], K indicates a blankingtime scaling factor, and J indicates a scaling factor weighting.

By using C′ and M′, a horizontal blanking duty H Blk Duty is obtained byEquation (3) as follows.H Blk Duty=C′−(M′/fH)  (3)

Further, the cycle tH [μS] of the horizontal synchronization signalSYNCH is obtained by Equation (4) as follows.tH=10³ /fH  (4)

Further, based on the horizontal blanking duty H Blk Duty and the cycletH of the horizontal synchronization signal SYNCH, a horizontal blankingperiod (non-active interval) H. Blk [μs] is obtained by Equation (5) asfollows.H. Blk=H Blk Duty*tH  (5)

Further, a pulse width interval H. Sync [μs] of the horizontalsynchronization signal SYNCH is 8% of the cycle tH of the horizontalsynchronization signal SYNCH according to the GTF Standard, so that thisH. Sync is obtained by Equation (6) as follows.H. Sync=tH*0.08  (6)

The GTF Standard defines that a trailing edge of the horizontalsynchronization signal SYNCH be placed at a center of the horizontalblanking period, so that the length t1 [μs] of the front-side frontporch FPH of the horizontal synchronization signal SYNCH and thetotal-sum length t2 [μs] of the horizontal synchronization signal SYNCHand its rear-side back porch BPH are obtained by Equations (7) and (8),respectively.t 1=H. Blk/2−H. Sync  (7)t 2=H. Blk/2+H. Sync  (8)

Then, the length t3 of the horizontal active interval ACTH sandwiched bythe back porch BPH and the front porch FPH is obtained by Equation (9)as follows.t 3=tH−(t 1+t 2)  (9)

The following will give an example of calculating each value in anactual case where the input video signal represents an image signalcomprised of 800×600, its horizontal synchronization frequency fH is 64[kHz], and its vertical synchronization frequency fV is 100.63 [Hz].

In this case, default values of C=40 [%], J=20 [%], M=600 [%/kHz] andK=128 are used to obtain C′=30 and M′=300 by Equations (1) and (2).Further, these values of C′ and M′ are used to obtain H Blk Duty-25.3125[%] by Equation (3). Further, tH=15.625 [μs] is obtained by Equation (4)and H. Blk=3.955 [μs] is obtained by Equation (5) and, further, H.Sync=1.25 [μs] is obtained by Equation (6). Further, t1=0.728 [μs],t2=3.228 [μs] and t3=11.669 [μs] are obtained by Equations (7), (8), and(9), respectively.

(B) Calculation of the Items of Vertical Timing Data L1, L2, and L3:

The total number of vertical lines LV indicates verticalcycle/horizontal cycle and is obtained by Equation (10) as follows.LV=(1/fV)÷(1/(fH×10³))  (10)

Further, the GTF Standard defines that a total-sum width of the verticalsynchronization signal SYNCV and its rear-side back porch BPV be 550[μs], so that the total-sum length L2 [lines] of the verticalsynchronization signal SYNCV and its rear-side back porch BPV isobtained by Equation (11) as follows.L 2=550/(10³ /fH)  (11)

Further, the GTF Standard defines that the length L1 of the front-sidefront porch FPV of the vertical synchronization signal SYNCV be fixed toone line. That is, L1=1 [line]. Further, the length L3 [lines] of thevertical active interval ACTV sandwiched by the back porch BPV and thefront porch FPV is obtained by Equation (12) as follows.L 3=LV−(L 1+L 2)  (12)

The following will give an example of calculating each value in anactual case where the input video signal represents an image signalcomprised of 800×600, its horizontal synchronization frequency fH is 64[kHz], and its vertical synchronization frequency fV is 100.63 [Hz].

In this case, LV=636 [lines] is obtained by Equation (10). L2=35 [lines]and L3=600 [lines] are obtained by Equations (11) and (12),respectively. Note here that L1=1 [line] as described above.

FIG. 2 indicates contents of the adjustment parameter table 12 b in thenonvolatile memory 12. This adjustment parameter table 12 b stores theadjustment parameters with them being associated with each of the kindsof the video signal (which are identified by a combination of thehorizontal synchronization frequency fH and the vertical synchronizationfrequency fV), so that each time a new kind of the video signal isinput, the corresponding new data (one suite of adjustment parameters)is registered therein additionally.

It is to be noted that the adjustment parameters include a horizontalsize parameter SH for adjusting a horizontal size of the image region ofthe screen of the CRT20, a horizontal position parameter PH foradjusting a horizontal position of the image region thereof, a verticalsize parameter SV for adjusting a vertical size of the image regionthereof, and a vertical position parameter PV for adjusting a verticalposition of the image region thereof.

This adjustment parameter table 12 b is referenced by the main controlportion 11 each time a new kind of the video signal is input, to displayan image on the screen of the CRT20 based on the adjustment parametersthus retrieved. However, if no adjustment parameter relative to therelevant kind of the video signal has been registered in the adjustmentparameter table 12 b, the main control portion 11 calculates the itemsof horizontal timing data t1, t2, and t3 and the items of verticaltiming data L1, L2, and L3 based on the horizontal synchronizationfrequency fH and the vertical synchronization frequency fV, to obtainthe adjustment parameters by using these items of the timing data,thereby displaying the image on the screen of the CRT20 based on theadjustment parameters thus obtained.

FIG. 3 indicates contents of the intrinsic property data storage area 12c in the nonvolatile memory 12. As described above, this intrinsicproperty data storage area 12 c is an area which stores property dataindicating intrinsic display properties of the image display device. Theitems of property data are obtained by measurement when a testing videosignal is actually input at a factory beforehand.

As shown in FIG. 3, the property data contains data indicating anassociation relationship between physical sizes D1 and D2 of thehorizontal image region width on the screen and horizontal sizeadjustment parameters SH1 and SH2 in a case where the testing videosignal is input and an active ratio r0 of this video signal (ratio ofthe length t3 of the horizontal active interval ACTH with respect to alength (tH−t4) of an interval obtained by subtracting the length t4 ofthe horizontal deflection pulse 23 from the cycle tH). These items ofdata are used when obtaining a target value of the horizontal sizeadjustment parameter SH as described above.

Further, as shown in FIG. 3, the property data contains also dataindicating characteristics of a dependency of a horizontal offset ratioδrH on a horizontal synchronization frequency. Note here that thehorizontal offset ratio δrH refers to a ratio of a horizontal offset δHwith respect to the horizontal frequency tH as described later. Forexample, in an example shown in FIG. 3, data is stored which indicatesthat when the frequency fH of the horizontal synchronization signalSYNCH takes on values of fH1, fH2, fH3 and fH4, the horizontal offsetratio δrH must be set to δrH1, δrH2, δrH3 and δrH4, respectively inorder to place the image region at a horizontal center of the screen.Further, as shown in FIG. 3, the property data contains also acorrelation between ΔH1, ΔH2 as values of a lapse of time ΔH(hereinafter referred to as “delay”) from a beginning of the horizontalsynchronization signal SYNCH to a trailing edge of the horizontaldeflection pulse 23 and horizontal position parameters Ph1, PH2, asshown in FIGS. 4A and 4B. These items of data are used when obtaining atarget value of the horizontal position adjustment parameter PH asdescribed above.

Although the above description has been made by showing only theproperty data relative to the horizontal direction in FIG. 3, theintrinsic property data storage area 12 c also stores similar propertydata relative to the vertical direction so that it may be referencedwhen obtaining the vertical size adjustment parameter SV or the verticalposition adjustment parameter PV.

The following will describe operations of the image display device 100described above with reference to FIG. 6. In the following description,mainly the operations of the main control portion 11 are explained, thusomitting explanation of the other portions.

First, when the input video signal 21 is input to the video outputcircuit 13, the main control portion 11 instructs the video signalmeasurement circuit 16 to measure a horizontal synchronization frequencyfH and a vertical synchronization frequency fV of the input video signal21, thereby acquiring measurement results at step ST1.

Next, at step ST2, the main control portion 11 searches the adjustmentparameter table 12 b (see FIG. 2) by using these acquiredsynchronization frequencies fH and fV as a retrieval key. At step ST3,it decides whether there are adjustment parameters that match thesesynchronization frequencies fH and fV. If there are any adjustmentparameters that match the acquired synchronization frequencies fH andfV, it goes to step ST4 wherein these adjustment parameters are read outof the adjustment parameter table 12 b to be set to the horizontaldeflection control circuit 14 and the vertical deflection controlcircuit 15. Specifically, these read out horizontal size adjustmentparameter SH and horizontal position adjustment parameter PH are set tothe horizontal deflection control circuit 14 and these read out verticalsize adjustment parameter SV and vertical position adjustment parameterPV are set to the vertical deflection control circuit 15.

If there are no adjustment parameters in the adjustment parameter table12 b that match the detected synchronization frequencies fH and fV, themain control portion 11 calculates the items of horizontal timing datat1, t2 and t3 and the items of vertical timing data L1, L2 and L3 byperforming the above-mentioned arithmetic operations based on thesesynchronization frequencies fH and fV at step ST5.

Next, at step ST6, the main control portion 11 performs a predeterminedarithmetic operation, which will be described, using the calculatedtiming data, thus calculating adjustment parameters. Then, the maincontrol portion 11 additionally registers these obtained adjustmentparameters in the adjustment parameter table 12 b with them beingassociated with the horizontal synchronization frequencies fH and fV atstep ST7 and also, at step ST4, sets the obtained adjustment parametersto the horizontal deflection control circuit 14 and the verticaldeflection control circuit 15.

The horizontal deflection control circuit 14, to which the main controlportion 11 sets the horizontal size adjustment parameter SH and thehorizontal position adjustment parameter PH, outputs the horizontaldeflection control signal to the horizontal deflection pulse outputcircuit 18 at a timing in accordance with these adjustment parameters,and then the horizontal deflection pulse output circuit 18 performssignal processing on this horizontal deflection control signal to outputthe horizontal deflection pulse 23 and apply it to the horizontaldeflection yoke (not shown) of the CRT20. On the other hand, thevertical deflection control circuit 15, to which the main controlportion 11 sets the vertical size adjustment parameter SV and thevertical position adjustment parameter PV, outputs the verticaldeflection control signal to the vertical deflection pulse outputcircuit 19 at a timing in accordance with these adjustment parameters,and then the vertical deflection pulse output circuit 19 performs thesignal processing on this vertical deflection control signal to outputthe vertical deflection pulse 24 and apply it to the vertical deflectionyoke (not shown) of the CRT20.

This CRT20 is supplied with the RGB video signal 22 generated from theinput video signal 21 at the video output circuit 13. Therefore, on thescreen of the CRT20, an image having appropriate size and position isalways displayed irrespective of the kind of the input video signal 21.

The following will describe a method for calculating adjustmentparameters by the main control portion 11.

The horizontal size adjustment parameter SH and the horizontal positionadjustment parameter PH, which are horizontal adjustment parameters, aredefined as functions given in the following Equations (13) and (14),respectively.SH=f(t 1, t 2, t 3, D 1, D 2)  (13)PH=g(t 1, t 2, t 3, δrH 1, δrH 2, δrH 3, δrH 4, ΔH 1, ΔH 2, fH)  (14)

-   -   where t1, t2 and t3 indicate quantities defined in FIG. 4, of        which values are obtained using the horizontal synchronization        frequency fH and the vertical synchronization frequency fV,        respectively, as described above. D1 and D2 indicate physical        sizes of the image region width in the horizontal direction on        the screen when two-point adjustment is performed by inputting        the testing video signal; δrH1, δrH2, δrH3 and δrH4 indicate        horizontal offset ratios represented by the horizontal offset δH        with respect to the horizontal cycle tH; and ΔH1 and ΔH2        indicate a delay ΔH shown in FIG. 4. These items of data are        stored in the intrinsic property data storage area 12 c shown in        FIG. 3. fH indicates a frequency of the horizontal        synchronization signal SYNCH and is obtained by measuring the        input video signal 21.

If an unknown video signal is input, its synchronization frequencies fHand fV are detected and used to calculate the items of timing data t1,t2 and t3, while D1, D2, etc. are read out of the intrinsic propertydata storage area 12 c, so that by applying Equations (13) and (14) tothese, the horizontal size adjustment parameter SH and the horizontalposition adjustment parameter PH can be obtained. Then, by outputtingthese adjustment parameters to the horizontal deflection control circuit14, a size and a position of the image region in the horizontaldirection are adjusted properly. The following will be further describedon the method more in detail with reference to FIGS. 7-9.

First, how to obtain the horizontal size adjustment parameter SH isdescribed with reference to FIG. 7. First, from the intrinsic propertydata storage area 12 c (see FIG. 3) of the nonvolatile memory 12,physical sizes D1 and D2 of the horizontal width of the image region ofthe screen and the corresponding horizontal size adjustment parametersSH1 and SH2 and an active ratio r0 are read, so that based on thesevalues, horizontal raster sizes D1/r0 and D2/r0 at two adjustment pointsare calculated. Here, the horizontal raster size refers to a horizontalscanning width. In such a manner, a horizontal raster size vs. thehorizontal size adjustment parameter SH interpolation line such as shownin FIG. 7 is obtained. In this case, the horizontal raster size issupposed to change linearly with respect to the horizontal sizeadjustment parameter.

Next, based on the horizontal synchronization frequency fH and thevertical synchronization frequency fV that are detected from the inputvideo signal 21, the items of timing data t1, t2, and t3 are calculated.Then, an active ratio r of the input video signal is calculated usingthe following Equation (15).r=t 3/(tH−t 4)=t 3/(t 1+t 2+t 3−t 4)  (15)

Then, a target physical size DT of the horizontal width of the imageregion is divided by the active ratio r obtained by Equation (15), toobtain a target value of the raster size DT/r.

Next, from the interpolation line shown in FIG. 7, such a horizontalsize adjustment parameter SHT that the raster size may be the value ofDT/r thus obtained is obtained. By outputting this horizontal sizeadjustment parameter SHT to the horizontal deflection control circuit14, the horizontal size of the image region of the screen is adjustedproperly.

Next, how to obtain the horizontal position adjustment parameter PH isdescribed with reference to FIGS. 8 and 9. First, from the intrinsicproperty data area 12 c (see FIG. 3) of the nonvolatile memory 12, datathat indicates characteristics of a dependency of the horizontal offsetratio on the horizontal period frequency, that is, the horizontal offsetratios δrH1, δrH2, δrH3, and δrH4 that respectively correspond to thefrequencies fH1, fH2, fH3 and fH4 of the horizontal synchronizationsignal SYNCH are read out in the example shown in FIG. 3 and, based onthese values, a horizontal synchronization frequency fH vs. horizontaloffset ratio δrH interpolation line as shown in FIG. 8 is obtained.

Next, from the interpolation line shown in FIG. 8, a horizontal offsetratio δrHT that corresponds to a target frequency fHT (that is, thehorizontal synchronization frequency fH of the input video signal 21) isobtained.

As is clear from FIG. 4, a delay ΔH (that is, a lapse of time from thebeginning of the horizontal synchronization signal SYNCH to the trailingedge of the horizontal deflection pulse 23) is given by the followingEquation (16).ΔH=(t 2−t 1+t 4)/2−δrH×tH  (16)

Then, by substituting a target value δrHT as the offset ratio δrH ofEquation (16), a target delay ΔHT is obtained.

Next, the main control portion 11 reads out of the intrinsic propertydata storage area 12 c (see FIG. 3) delays ΔH1 and ΔH2 and thecorresponding horizontal position parameters PH1 and pH2, to obtain adelay ΔH vs. horizontal position parameter PH interpolation line asshown in FIG. 9. In this case, the delay ΔH is supposed to changelinearly with respect to the horizontal position parameter PH.

Next, the main control portion 11 obtains a horizontal positionadjustment parameter PHT that corresponds to the target delay ΔHTobtained by Equation (16), from the delay ΔH vs. horizontal positionparameter PH interpolation line shown in FIG. 9. By outputting thishorizontal position adjustment parameter PHT to the horizontaldeflection control circuit 14, the horizontal position of the imageregion of the screen is adjusted properly.

Although how to obtain the adjustment parameter in horizontal scanninghas been described above, the basic procedure is also the same with anadjustment parameter in vertical scanning. It is described briefly asfollows.

The vertical size adjustment parameter SV and the vertical positionadjustment parameter PV, which are vertical adjustment parameters, aredefined as functions given in the following Equations (17) and (18),respectively.SV=F(L 1, L 2, L 3, E 1, E 2)  (17)PV=G(L 1, L 2, L 3, fV)  (18)

In this case, L1, L2 and L3 indicate quantities defined in FIG. 5, ofwhich values are obtained using the horizontal synchronization frequencyfH and the vertical synchronization frequency fV, respectively, asdescribed above. E1 and E2 indicate physical sizes of the image regionin the horizontal direction on the screen when two-point adjustment isperformed by actually inputting the testing video signal and are storedin the intrinsic property data storage area 12 c shown in FIG. 3 (whichis not shown in FIG. 3 though). fV indicates a frequency of the verticalsynchronization signal SYNCV and is obtained by measuring the inputvideo signal 21.

If an unknown video signal is input, its synchronization frequencies fHand fV are detected and used to calculate the items of timing data L1,L2 and L3, while E1 and E2 (not shown) are read out of the intrinsicproperty data storage area 12 c, so that by applying Equations (17) and(18) to these, the vertical size adjustment parameter SV and thevertical position adjustment parameter PV can be obtained. Then, byoutputting these adjustment parameters to the vertical deflectioncontrol circuit 15, the size and the position of the image region areadjusted properly also in the vertical direction.

In such a manner, by the present embodiment, the horizontalsynchronization frequency fH and the vertical synchronization frequencyfV detected from the input video signal 21 are used to calculate theitems of horizontal timing data t1, t2, and t3 and the items of verticaltiming data L1, L2, and L3 that are relative to a waveform of this inputimage signal 21, and these items of timing data are used to calculateand use the adjustment parameters SH, PH, SV and PV for adjusting animage display state (display size, display position), to thus eliminatea necessity of storing the timing data that corresponds to a pluralityof kinds of input video signals, thereby saving on a memory capacity.

Further, in the present embodiment, by storing calculated adjustmentparameters SH, PH, SV and PV in the adjustment parameter table 12 b withthem being associated with the horizontal synchronization frequency fHand the vertical synchronization frequency fV, when predeterminedadjustment parameters that corresponds to the horizontal synchronizationfrequency fH and the vertical synchronization frequency fV detected fromthe input video signal 21 is present in the adjustment parameter table12 b, an image relative to the input video signal 21 can be displayed onthe basis of the predetermined adjustment parameters (see ST3 and ST8 ofFIG. 6) to thereby immediately acquire the adjustment parameters fromthe adjustment parameter table 12 b, if the same kind of image signal isinput, without calculating timing data or adjustment parameters, inorder to reduce a lapse of time from a moment when the video signal isinput to a moment when the image is displayed, thus improving aresponse.

Although the first embodiment has been described to the effect that theinput video signal 21 conforms to the GTF Standard, any other inputvideo signal can be accommodated as far as the horizontal and verticaltiming data can be calculated on the basis of the horizontalsynchronization frequency and the vertical synchronization frequency.

The following will describe the second embodiment of the presentinvention. FIG. 10 shows a configuration of an image display device 100Aaccording to the second embodiment. The image display device 100A isconstituted as a multi-scanning type monitor that can accommodate aplurality of kinds of image signals (hereinafter called “video signals”)including an image signal conforming to the VESA's GRF Standard.Components of FIG. 10 that correspond to those of FIG. 1 are indicatedby the same reference symbols and explanation thereof is omitted.

The image display device 100A has a video signal measurement circuit 16Ain place of the video signal measurement circuit 16 in the image displaydevice 100 shown in FIG. 1. To the video signal measurement circuit 16A,the same signal as the input video signal 21 is input from a videooutput circuit 13. The video signal measurement circuit 16A measuresfrequencies (horizontal synchronization frequency fH and verticalsynchronization frequency fV) of a synchronization signal in the inputvideo signal 21 and a polarity of the synchronization signal and sendsmeasurement results as kind data to a main control portion 11.

Further, the image display device 100A has a nonvolatile memory 12A inplace of the nonvolatile memory 12 in the image display device 100 shownin FIG. 1. The nonvolatile memory 12A is constituted of, for example, anElectrically Erasable and Programmable ROM (EEPROM), comprising at leasta timing data table 12 a and an intrinsic property data storage area 12c.

The intrinsic property data storage area 12 c is the same as thatcontained in the nonvolatile memory 12 in the image display device 100shown in FIG. 1 (see FIG. 3). The timing data table 12 a is created bystoring various items of timing data correlated to each of the kinds ofthe video signals at a factory beforehand.

FIG. 11 shows contents of the timing data table 12 a in the nonvolatilememory 12A. The timing data table 12 a is created and written into thenonvolatile memory 12A at the factory etc. beforehand, having such aconfiguration that timing data 122 relative to a waveform of each of thevideo signals and a signal type are correlated to each other for each ofthe kinds (kind data 121) of the video signal expected to be usedbeforehand.

The kind data 121 contains a frequency and a polarity of each of thehorizontal and vertical synchronization signals, while the timing data122 contains items of horizontal timing data t1, t2, t3, and t4 anditems of vertical timing data L1, L2, and L3. These items of horizontaltiming data t1, t2, and t3 and the items of vertical timing data L1, L2,and L3 are the same as those described with the above first embodimentand explanation thereof is omitted.

In an example shown, timing data relative to a video signal etc. havinga horizontal synchronization signal having, for example, a frequency of81.9 kHz and a negative polarity [N] and a vertical synchronizationsignal having a frequency of 75 Hz and the negative polarity [N] isrecorded. It is to be noted that the signal type may be, for example, aseparation type (SEP) wherein horizontal and vertical synchronizationsignals are separated from a substantial portion (active interval) ofthe video signal and a composite type (COMP) wherein they are mixed withthe substantial portion of the video signal.

Further, the image display device 100A has a delay measurement circuit30. The delay measurement circuit 30 is supplied with a horizontalsynchronization signal SYNCH output from the video signal measurementcircuit 16A as well as with a horizontal deflection pulse 23 output froma horizontal deflection pulse output circuit 18. The delay measurementcircuit 30 measures a lapse of time from a beginning of the horizontalsynchronization signal SYNCH to a trailing edge of the horizontaldeflection pulse 23 as a delay ΔH (see FIGS. 4A and 4B) and sendsmeasurement results to the main control portion 11.

Other components of the image display device 100A are the same as thosein configuration of the image display device 100 shown in FIG. 1.

The following will describe operations of the image display device 100Awith reference to FIG. 12. In the following description, mainly theoperations of the main control portion 11 are described, omitting theother portions.

First, when the input video signal 21 is input to the video outputcircuit 13, the main control portion 11 instructs the video signalmeasurement circuit 16A to measure frequencies (horizontalsynchronization frequency fH and vertical synchronization frequency fV)of a synchronization signal in the input video signal 21, therebyacquiring measurement results as kind data at step ST11.

Next, at step ST12, the main control portion 11 searches the adjustmentparameter table 12 a (see FIG. 11) by using the acquired kind data as aretrieval key. At step ST13, it decides whether there is timing datathat matches the kind data. If there is any timing data that matches theacquired kind data, it goes to step ST14.

If there is no timing data that matches the acquired kind data, on theother hand, the main control portion 11 uses a horizontalsynchronization frequency fH and a vertical synchronization frequency fVof the acquired kind data, to calculate the items of horizontal timingdata t1, t2, and t3 and the items of vertical timing data L1, L2 and L3and the process then goes to step ST14. How to calculate the timing datais the same as that described with the first embodiment and soexplanation thereof is omitted here.

At step ST14, the main control portion 11 uses the timing data tocalculate adjustment parameters (horizontal size adjustment parameterSH, horizontal position adjustment parameter PH, vertical sizeadjustment parameter SV, and vertical size adjustment parameter PV). Howto calculate these adjustment parameters is the same as that describedwith the first embodiment and explanation thereof is omitted here.

Next, at step ST16, the main control portion 11 sets the calculatedadjustment parameters to a horizontal deflection control circuit 14 anda vertical deflection control circuit 15.

The horizontal deflection control circuit 14, to which the main controlportion 11 sets the horizontal size adjustment parameter SH and thehorizontal position adjustment parameter PH, outputs a horizontaldeflection control signal to the horizontal deflection pulse outputcircuit 18 at a timing in accordance with these adjustment parameters,and then the horizontal deflection pulse output circuit 18 performssignal processing on this horizontal deflection control signal to outputthe horizontal deflection pulse 23 and apply it to a horizontaldeflection yoke (not shown) of a CRT20.

On the other hand, the vertical deflection control circuit 15, to whichthe main control portion 11 sets the vertical size adjustment parameterSV and the vertical position adjustment parameter PV, outputs a verticaldeflection control signal to a vertical deflection pulse output circuit19 at a timing in accordance with these adjustment parameters, and thenthe vertical deflection pulse output circuit 19 performs the signalprocessing on this vertical deflection control signal to output avertical deflection pulse 24 and apply it to a vertical deflection yoke(not shown) of the CRT20.

Further, this CRT20 is supplied with an RGB video signal 22 generatedfrom the input video signal 21 at the video output circuit 13.Therefore, on the CRT20, an image having appropriate size and positionis always displayed irrespective of the kind of the input video signal21.

If, in this case, a deflection system is not deteriorated over time, bysetting the calculated horizontal position adjustment parameter PH tothe horizontal deflection control circuit 14, a lapse of time from thebeginning of the horizontal synchronization signal SYNCH to the trailingedge of the horizontal deflection pulse 23, that is, a delay ΔH becomesequal to a target delay ΔH, thus placing a horizontal display positionat a right position.

If the deflection system is deteriorated over time, on the other hand,the delay ΔH is different from the target delay ΔHT, resulting in thehorizontal display position being shifted from the right position.Therefore, at step ST17, the main control portion 11 then performsconvergent processing on the delay ΔH so that the delay may be equal tothe target delay ΔHT and then ends the processing.

The following will describe processing operations for performingconvergent processing on the delay ΔH, with reference to FIG. 13.

First, at step ST21, the main control portion 11 instructs the delaymeasurement circuit 30 to measure a delay ΔH, thus acquiring ameasurement result. At step ST22, the main control portion 11 decideswhether the delay ΔH is equal to the target delay ΔHT. Note here thatthe target delay ΔHT is obtained by substituting a target value δrHTobtained from an interpolation line shown in FIG. 8 into δrH of Equation(16).

If the delay ΔH is not equal to the target delay ΔHT, the main controlportion 11 decides whether the delay ΔH is larger than the target delayΔHT, at step ST23. If the delay ΔH is larger than the target delay ΔHT,the main control portion 11 subtracts one alteration unit from a valueof the horizontal position adjustment parameter PH set to the horizontaldeflection control circuit 14 and re-sets it at step 24, and then theprocess returns to step ST21. If the delay ΔH is smaller than the targetdelay ΔHT, on the other hand, the main control portion 11 adds onealteration unit to the value of the horizontal position adjustmentparameter PH set to the horizontal deflection control circuit 14 andre-sets it at step ST 25 and then the process returns to step ST21.

Further, if it is decided that the delay ΔH is equal to the target delayΔHT at step ST22, the convergent processing ends. It is to be noted thatthe delay ΔH being equal to the target delay ΔHT refers not only to acase where the delay ΔH coincides with the target delay ΔHT completelybut also to a case where the delay ΔH falls in a range having the targetdelay ΔHT at a center thereof and a predetermined margin on its bothsides.

In such a manner, by the second embodiment, the convergent processing isperformed on the delay ΔH so that it may be equal to the target delayΔHT, thereby allowing the horizontal display position to be placed atthe right position even if the deflection system is deteriorated overtime.

It is to be noted that, in the second embodiment, although notdescribed, the same adjustment parameter table 12 b as that of the firstembodiment may be provided. In this case, adjustment parameters obtainedat step ST14 are registered in the adjustment parameter table 12 b withthem being associated with the kind data obtained from the input videosignal 21. Then, in a case where the input video signal is newly input,if the adjustment parameters that correspond to the kind data obtainedtherefrom are present in the adjustment parameter table 12 b, theadjustment parameters that correspond to the input video signal 21 areread out of the adjustment parameter table 12 b and used withoutcalculating the adjustment parameter.

Although the first embodiment described above has not performed theconvergent processing such as that performed in the second embodiment,the convergent processing may be performed much the same way as thesecond embodiment so that the delay ΔH may be equal to the target delayΔHT. In this case, for example, after step ST4 of FIG. 6, a step forperforming the convergent processing (see step ST17 of FIG. 12) might beinserted. By performing the convergent processing in such a manner, thehorizontal display position can be placed at the right position even ifthe deflection system is deteriorated over time.

It is to be noted that although the embodiments described above haveobtained an adjustment parameter using property data specific to eachdevice (see FIG. 3), the present invention is not limited thereto; forexample, the same fixed data may be used as the property data uniformlyon all devices as far as they have a slight difference from each other.

Further, although the embodiments described above have obtained theadjustment parameters according to a procedure described along FIGS.7-9, any other procedures may be followed.

According to the present invention, the horizontal synchronizationfrequency and the vertical synchronization frequency detected from theinput video signal are used to calculate timing data relative to awaveform of the input image signal, then the timing data is used toobtain adjustment parameters each for adjusting an image display state,and based on the adjustment parameters an image relative to the inputimage signal is displayed. It eliminates a necessity of storing thetiming data that corresponds to the plurality of kinds of image signalsin order to obtain adjustment parameters that correspond to a pluralityof kinds of image signals, thus enabling saving on a memory capacity.

Further, according to the present invention, by storing the calculatedadjustment parameters in storage means with them being associated withthe horizontal synchronization frequency and the verticalsynchronization frequency, when predetermined adjustment parameters thatcorrespond to the horizontal synchronization frequency and the verticalsynchronization frequency detected from the input video signal arepresent in the storage means, an image relative to the input videosignal can be displayed on the basis of the predetermined adjustmentparameters to thereby immediately acquire the same kind of image signalfrom the storage means, if the same kind of image signal is input,without calculating timing data or adjustment parameters, in order toreduce a lapse of time from a moment when the image signal is input to amoment when the image is displayed, thus improving a response.

Further, according to the present invention, timing data relative to awaveform of the input image signal is used to calculate the adjustmentparameters each for adjusting the image display state, and thisadjustment parameter is set to a deflection control circuit, so thatsubsequently a delay of the deflection pulse with respect to thehorizontal synchronization signal of the input image signal is measured,to alter a value of the horizontal position parameter so that the delaymay be equal to a target delay and re-set it to the deflection controlcircuit, thus enabling placing the horizontal display position at theright position even if the deflection system is deteriorated over time.

INDUSTRIAL APPLICABILITY

As described above, image display device and method according to thepresent invention are well applied to a so-called multi-scanning typemonitor having a function that can accommodate various image signals.

1. An image display device comprising: detection means for detecting ahorizontal synchronization frequency and a vertical synchronizationfrequency of an input image signal; first arithmetic operation means forcalculating timing data relative to a waveform of said input imagesignal using the horizontal synchronization frequency and the verticalsynchronization frequency that are detected by said detection means;second arithmetic operation means for calculating an adjustmentparameter for adjusting an image display state using the timing datacalculated by said first arithmetic operation means; and image displaymeans for displaying an image relative to of said input image signalbased on the adjustment parameter calculated by said second arithmeticoperation means.
 2. The image display device according to claim 1,further comprising: storage means for storing the adjustment parametercalculated by said second arithmetic operation means associated with thehorizontal synchronization frequency and the vertical synchronizationfrequency detected by said detection means; decision means for decidingwhether a predetermined adjustment parameter corresponds to thehorizontal synchronization frequency and the vertical synchronizationfrequency detected by said detection means is present in said storagemeans; and control means for controlling said image display means fordisplaying an image relative to said input image signal based on saidpredetermined adjustment parameter when said decision means has decidedthat said predetermined adjustment parameter is present in said storagemeans.
 3. An image display method comprising the steps of: detecting ahorizontal synchronization frequency and a vertical synchronizationfrequency of an input image signal; calculating timing data relative toa waveform of said input image signal using said horizontalsynchronization frequency and said vertical synchronization frequencydetected in said step of detecting; calculating an adjustment parameterfor adjusting an image display state using said calculated timing data;and displaying an image of said input image signal based on saidadjustment parameter calculated in said step of calculating.
 4. Theimage display method according to claim 3, further comprising the stepsof: storing said calculated adjustment parameter in data storage meansso as to be associated with said horizontal synchronization frequencyand said vertical synchronization frequency detected in said step ofdetecting; deciding whether a predetermine adjustment parametercorresponding to said detected horizontal and vertical synchronizationfrequencies is present in said data storage means; and when saidpredetermined adjustment parameter is decided to be present, controllingthe displaying of an image relative to said input image signal based onsaid predetermined adjustment parameter, without calculating said timingdata and without calculating said adjustment parameter.
 5. An imagedisplay device comprising: timing data acquisition means for acquiringtiming data relative to a waveform of an input image signal; calculationmeans for calculating adjustment parameters for adjusting an imagedisplay state using the timing data acquired by said timing dataacquisition means; setting means for setting the adjustment parameterscalculated by said calculation means to a deflection control circuit;delay measurement means for measuring a delay of a deflection pulse withrespect to a horizontal synchronization signal of said input imagesignal; and re-setting means for altering a value of a horizontalposition adjustment parameter of said adjustment parameters, wherein thehorizontal position adjustment parameter adjusts an image regionposition in a horizontal direction, so that a delay measured by saiddelay measurement means is equal to a target delay and for re-settingthe delay.
 6. The image display device according to claim 5, whereinsaid timing data acquisition means comprises: data storage means forstoring timing data relative to respective signal waveforms for each ofa plurality of different kinds of image signals; detection means fordetecting a kind of the input image signal; and read-out means forreading out of said data storage means timing data corresponding to thekind of the input image signal detected by said detection means.
 7. Theimage display device according to claim 6, wherein said detection meanscomprises first detection means, said calculation means comprises firstcalculation means, and said timing data acquisition means furthercomprises: second detection means for detecting a horizontalsynchronization frequency and a vertical synchronization frequency ofsaid input image signal; and second calculation means for calculatingtiming data relative to a waveform of said input image signal using thehorizontal synchronization frequency and the vertical synchronizationfrequency detected by said second detection means, when there is notiming data that corresponds to the kind of the input image signaldetected by said first detection means in said data storage means. 8.The image display device according to claim 5, wherein said calculationmeans comprises first calculation means and said timing data acquisitionmeans comprises: detection means for detecting a horizontalsynchronization frequency and a vertical synchronization frequency ofsaid input image signal; and second calculation means for calculatingtiming data relative to a waveform of said input image signal using thehorizontal synchronization frequency and the vertical synchronizationfrequency detected by said detection means.
 9. An image display methodcomprising the steps of: acquiring timing data relative to a waveform ofan input image signal; calculating adjustment parameters each foradjusting an image display state using said acquired timing data;setting the calculated adjustment parameters to a deflection controlcircuit; measuring a delay of a deflection pulse with respect to ahorizontal synchronization signal of said input image signal; andaltering a value of a horizontal position adjustment parameter of theadjusting parameters, the horizontal position adjustment parameteradjusting image region position in a horizontal direction, so that themeasured delay may be equal to a target delay and for re-setting it tothe deflection control circuit.
 10. The image display method accordingto claim 9, wherein said step of acquiring timing data comprises thesteps of: detecting a kind of said input image signal; and readingtiming data that corresponds to said detected kind of input image signalout of data storage means in which timing data relative to respectivesignal waveforms for each of the kinds of said image signal is stored.11. The image display method according to claim 10, wherein said step ofacquiring timing data comprises the steps of: detecting a horizontalsynchronization frequency and a vertical synchronization frequency ofsaid input image signal; and calculating timing data relative to awaveform of said input image signal using said detected horizontal andvertical synchronization frequencies when there is no timing data thatcorresponds to said detected kind of the input image signal stored insaid data storage means.
 12. The image display method according to claim9, wherein said step of acquiring timing data comprises the steps of:detecting a horizontal synchronization frequency and a verticalsynchronization frequency of said input image signal; and calculatingtiming data relative to a waveform of said input image signal using saiddetected horizontal and vertical synchronization frequencies.